Activity-by-Contact model of enhancer specificity from thousands of CRISPR perturbations [ChIP-Seq]

Mammalian genomes harbor millions of noncoding elements called enhancers that quantitatively regulate gene expression, but the mechanisms that determine which enhancers regulate which genes are not well understood. Here we describe a high-throughput approach, based on CRISPR interference, RNA FISH, and flow cytometry (CRISPRi-FlowFISH), to perturb enhancers in the genome and apply it to test >3,000 potential regulatory enhancer-gene connections across multiple genomic loci. Seemingly complex patterns of enhancer-gene connections in this dataset can largely be explained by a simple quantitative Activity-by-Contact (ABC) model, in which the effect of a candidate enhancer on a target gene is predicted by the intrinsic activity of the enhancer multiplied by the contact frequency between the enhancer and promoter. This ABC score can identify regulatory enhancer-gene connections and predict their quantitative effects from DNase-Seq, H3K27ac ChIP-seq, and Hi-C measurements. The ABC model can explain even complex regulatory phenomena including the ability of an enhancer to “skip” over one gene to regulate a more distant one. Our approach provides a foundation for dissecting mechanisms of enhancer-gene regulation and predicting enhancer-gene connections across cell types. Overall design: H3K27ac ChIP-seq was used to profile F2-1 mESCs in 2 technical replicates.